1. Highly-Ionizing Particles in Supersymmetric Models John Ellis King’s College London & CERN

2. Particles + spartners No highly-charged particles expected, BUT …. 2 Higgs doublets, coupling μ, ratio of v.e.v.’s = tan β Unknown supersymmetry-breaking parameters: Scalar masses m 0, gaugino masses m 1/2, trilinear soft couplings A λ, bilinear soft coupling B μ Often assume universality: Single m 0, single m 1/2, single A λ, B μ : not string? Called constrained MSSM = CMSSM Minimal Supersymmetric Extension of Standard Model (MSSM)

3. Mass Reach as Function of Energy & Luminosity

4. Lightest Supersymmetric Particle Stable in many models because of conservation of R parity: R = (-1) 2S –L + 3B where S = spin, L = lepton #, B = baryon # Particles have R = +1, sparticles R = -1: Sparticles produced in pairs Heavier sparticles  lighter sparticles Lightest supersymmetric particle (LSP) stable

5. Possible Nature of LSP No strong or electromagnetic interactions Otherwise would bind to matter Detectable as anomalous heavy nucleus Possible weakly-interacting scandidates Sneutrino (Excluded by LEP, direct searches) Lightest neutralino χ (partner of Z, H, γ) Gravitino (nightmare for astrophysical detection)

6. Scenarios for Metastable Sparticles Maybe R-parity not exact? – No stable sparticle Next-to-lightest sparticle (NLSP) may be long- lived – Could be charged or neutral Scenarios for long-lived NLSP: – Small mass difference from neutralino LSP – Gravitino LSP – Gluinos in split supersymmetry

7. Energy Loss and Range Singly-charged particles are highly-ionizing if moving slowly Small range in typical Detector materials

8. Next-to-Lightest Supersymmetric Particle (NLSP) ? In neutralino dark matter scenarios: – Lighter stau? Could be long-lived if m stau –m LSP small In gravitino dark matter scenarios: – Lighter stau, selectron or sneutrino? – Lighter stop squark? – gluino, …? Naturally long-lived – Decay interaction of gravitational strength

9. Parameter Plane in the CMSSM Excluded because stau LSP Excluded by b  s gamma Preferred (?) by latest g - 2 Assuming the lightest sparticle is a neutralino WMAP constraint on CDM density LHC JE, Olive & Spanos

10. Stau NLSP with Neutralino LSP Along coannihilation strip of CMSSM parameter space favoured by dark matter density Generally small stau- neutralino mass difference May well be < 2 GeV Favoured by LHC JE, Olive LHC

11. Stau NLSP with Neutralino LSP 2-, 3- or 4-body decays may dominate, depending on m stau –m LSP Lifetime > 100 ns for mass difference < m τ Jittoh, Sato, Shimomura, Yamanaka: hep-ph/0512197

12. Stau Lifetime in Gravitino Dark Matter Scenarios Gravitational-strength decay interaction Naturally long lifetime Hamaguchi, Nojiri, De Roeck: hep-ph/0612060

13. Sample Supersymmetric Parameter Plane with different NLSP Options Lighter stau Lighter selectron Tau sneutrino Electron sneutrino In gravitino dark matter scenario Ellis, Olive, Santoso: arXiv:0807.3736

14. More Planes with different NLSPs Lighter stau Lighter selectron Tau sneutrino Electron sneutrino In gravitino dark matter scenario Ellis, Olive, Santoso: arXiv:0807.3736

15. Gravitino Dark Matter Benchmark Models with Stau NLSP De Roeck, JE, Gianotti, Moortgat, Olive, Pape :hep-ph/0508198 Many τ’s in final states

16. Example of Stop NLSP in Gravitino Dark Matter Scenario Requires ‘careful’ choice of parameters Diaz-Cruz, JE, Olive, Santoso: hep-ph/0701229

17. More Examples of Gravitino Dark Matter Scenarios with Stop NLSP Requires ‘careful’ choice of parameters – but quite generic Diaz-Cruz, JE, Olive, Santoso: hep-ph/0701229

18. Stop Lifetime in CMSSM with Gravitino Dark Matter 2-body decays 3-body decays Diaz-Cruz, JE, Olive, Santoso: hep-ph/0701229

19. Stop the Lithium Problem Notorious Lithium problem of Big-Bang Nucleosynthesis Could be solved by metastable stop decays Kohri, Santoso: arXiv:0811.1119

20. Gluinos in Split Supersymmetry Long-lived because squarks heavy Possible gluino hadrons: Gluino-g, gluino-qqbar, gluino-qqq Is there a metastable charged gluino hadron? Gluino hadrons may flip charge as they pass through matter Gluino mesons may change into baryons: – e.g., gluino-uubar + uud  gluino-uud + uubar Hewitt, Lillie, Masip, Rizzo: hep-ph/0408248

21. Gluino Production at the LHC Large cross section @ LHC Significant fraction of charged particles emerge from the detector Hewitt, Lillie, Masip, Rizzo: hep-ph/0408248 Farrar, Mackeprang, Milstead, Roberts: arXiv:1011.2964

22. Production at the LHC

23. Kinematical Distributions for Stops Pseudo-rapidity distribution Velocity distribution Johansen, Edsjo, Hellman, Milstead: arXiv:1003.4540

24. Typical Velocities & Ranges De Roeck, JE, Gianotti, Moortgat, Olive, Pape: hep-ph/0508198 Hamaguchi, Nojiri, De Roeck: hep-ph/0612060 Some fraction of slow-moving charged particles

25. Searches at the LHC

26. CMS Search for Metastable Particles using Tracker only

27. CMS Search for Metastable Particles using Tracker and TOF

28. Water Trap Concept for Stopping Metastable Charged Particles Feng & Smith: hep-ph/0409278 Hope it does not leak! Energy distribution

29. Water Trap Concept for Stopping Metastable Charged Particles Feng & Smith: hep-ph/0409278 Angular distribution Number of trapped particles

30. Possible (Meta)stable Particle Stoppers Hamaguchi, Nojiri, De Roeck: hep-ph/0612060

31. Extract Cores from Surrounding Rock? Use muon system to locate impact point on cavern wall with uncertainty < 1cm Fix impact angle with accuracy 10 -3 Bore into cavern wall and remove core of size ~ 1cm × 1cm × 10m = 10 -3 m 3 Can this be done before staus decay? – Caveat radioactivity induced by collisions – Several technical stops each year Not possible if lifetime ~10 4 s, possible if ~10 6 s? De Roeck, JE, Gianotti, Moortgat, Olive, Pape :hep-ph/0508198

32. Summary Few prospects for multiply-charged sparticles Many prospects for long-lived singly-charged sparticles – Staus, stops, selectrons, … Some would be produced with low velocities, hence highly-ionizing Production rates within MoEDAL reach